At the Feather HUZZAH's heart is an ESP8266 WiFi microcontroller clocked at 80 MHz and at 3.3V logic. This microcontroller contains a Tensilica chip core as well as a full WiFi stack. You can progam the microcontroller using the Arduino IDE for an easy-to-run Internet of Things core. We wired up a USB-Serial chip that can upload code at a blistering 921600 baud for fast development time. It also has auto-reset so no noodling with pins and reset button pressings.

To make it easy to use for portable projects, we added a connector for any of our 3.7V Lithium polymer batteries and built in battery charging. You don't need a battery, it will run just fine straight from the micro USB connector. But, if you do have a battery, you can take it on the go, then plug in the USB to recharge. The Feather will automatically switch over to USB power when its available.

Auto-reset support for getting into bootload mode before firmware upload

9 GPIO pins - can also be used as I2C and SPI

1 x analog inputs 1.0V max

Built in 100mA lipoly charger with charging status indicator LED

Pin #0 red LED for general purpose blinking. Pin #2 blue LED for bootloading debug & general purpose blinking

Power/enable pin

4 mounting holes

Reset button

Comes fully assembled and tested, with a USB interface that lets you quickly use it with the Arduino IDE or NodeMCU Lua. (It comes preprogrammed with the Lua interpretter) We also toss in some header so you can solder it in and plug into a solderless breadboard. Lipoly battery and USB cable not included (but we do have lots of options in the shop if you'd like!)

Pinouts

Power Pins

BAT - this is the positive voltage to/from the JST jack for the optional Lipoly battery

USB - this is the positive voltage to/from the micro USB jack if connected

EN - this is the 3.3V regulator's enable pin. It's pulled up, so connect to ground to disable the 3.3V regulator

3V - this is the output from the 3.3V regulator, it can supply 500mA peak (try to keep your current draw under 250mA so you have plenty for the ESP8266's power requirements!)

Logic pins

This is the general purpose I/O pin set for the microcontroller. All logic is 3.3V

The ESP8266 runs on 3.3V power and logic, and unless otherwise specified, GPIO pins are not 5V safe! The analog pin is also 1.0V max!

Serial pins

RX and TX are the serial control and bootloading pins, and are how you will spend most of your time communicating with the ESP module

The TX pin is the output from the module and is 3.3V logic.

The RX pin is the input into the module and is 5V compliant (there is a level shifter on this pin)

These are connected through to the CP2104 USB-to-Serial converter so they should not be connected to or used unless you're super sure you want to because you will also be getting the USB traffic on these!

I2C & SPI pins

You can use the ESP8266 to control I2C and SPI devices, sensors, outputs, etc. While this is done by 'bitbanging', it works quite well and the ESP8266 is fast enough to match 'Arduino level' speeds.

In theory you can use any pins for I2C and SPI but to make it easier for people using existing Arduino code, libraries, sketches we set up the following:

I2C SDA = GPIO #4 (default)

I2C SCL = GPIO #5 (default)

If you want, you can connect to I2C devices using other 2 pins in the Arduino IDE, by calling Wire.pins(sda, scl) before any other Wire code is called (so, do this at the begining of setup() for example

Likewise, you can use SPI on any pins but if you end up using 'hardware SPI' you will want to use the following:

SPI SCK = GPIO #14 (default)

SPI MOSI = GPIO #13 (default)

SPI MISO = GPIO #12 (default)

GPIO pins

This breakout has 9 GPIO: #0, #2, #4, #5, #12, #13, #14, #15, #16 arranged at the top edge of the Feather PCB

All GPIO are 3.3V logic level in and out, and are not 5V compatible. Read the full spec sheet to learn more about the GPIO pin limits, but be aware the maximum current drawn per pin is 12mA.

These pins are general purpose and can be used for any sort of input or output. Most also have the ability to turn on an internal pullup. Many have special functionality:

GPIO #0, which does not have an internal pullup, and is also connected a red LED. This pin is used by the ESP8266 to determine when to boot into the bootloader. If the pin is held low during power-up it will start bootloading! That said, you can always use it as an output, and blink the red LED - note the LED is reverse wired so setting the pin LOW will turn the LED on.

GPIO #2, is also used to detect boot-mode. It also is connected to the blue LED that is near the WiFi antenna. It has a pullup resistor connected to it, and you can use it as any output (like #0) and blink the blue LED.

GPIO #15, is also used to detect boot-mode. It has a pulldown resistor connected to it, make sure this pin isn't pulled high on startup. You can always just use it as an output

GPIO #16 can be used to wake up out of deep-sleep mode, you'll need to connect it to the RESET pin

Also note that GPIO #12/13/14 are the same as the SCK/MOSI/MISO 'SPI' pins!

Analog Pins

There is also a single analog input pin called A. This pin has a ~1.0V maximum voltage, so if you have an analog voltage you want to read that is higher, it will have to be divided down to 0 - 1.0V range

Other control pins

We have a few other pins for controlling the ESP8266

RST - this is the reset pin for the ESP8266, pulled high by default. When pulled down to ground momentarily it will reset the ESP8266 system. This pin is 3.3V logic only

EN (CH_PD) - This is the enable pin for the ESP8266, pulled high by default. When pulled down to ground momentarily it will reset the ESP8266 system. This pin is 3.3V logic only

NC Pins

The rest of the pins are labeled NC which means Not Connected - they are not connected to anything and are there as placeholders only, to maintain physical compatibility with the other boards in the Feather line!

Assembly

We ship Feathers fully tested but without headers attached - this gives you the most flexibility on choosing how to use and configure your Feather

Header Options!

Before you go gung-ho on soldering, there's a few options to consider!

The first option is soldering in plain male headers, this lets you plug in the Feather into a solderless breadboard

Another option is to go with socket female headers. This won't let you plug the Feather into a breadboard but it will let you attach featherwings very easily

We also have 'slim' versions of the female headers, that are a little shorter and give a more compact shape

Finally, there's the "Stacking Header" option. This one is sort of the best-of-both-worlds. You get the ability to plug into a solderless breadboard and plug a featherwing on top. But its a little bulky

Soldering in Plain Headers

Prepare the header strip:

Cut the strip to length if necessary. It will be easier to solder if you insert it into a breadboard - long pins down

Add the breakout board:

Place the breakout board over the pins so that the short pins poke through the breakout pads

Power Management

Battery + USB Power

We wanted to make the Feather HUZZAH easy to power both when connected to a computer as well as via battery. There's two ways to power a Feather. You can connect with a MicroUSB cable (just plug into the jack) and the Feather will regulate the 5V USB down to 3.3V. You can also connect a 4.2/3.7V Lithium Polymer (Lipo/Lipoly) or Lithium Ion (LiIon) battery to the JST jack. This will let the Feather run on a rechargable battery. When the USB power is powered, it will automatically switch over to USB for power, as well as start charging the battery (if attached) at 100mA. This happens 'hotswap' style so you can always keep the LiPoly connected as a 'backup' power that will only get used when USB power is lost.

The above shows the Micro USB jack (left), Lipoly JST jack (top left), as well as the 3.3V regulator and changeover diode (just to the right of the JST jack) and the Lipoly charging circuitry (right below the regulator).

There's also a CHG LED next to the USB jack, which will light up while the battery is charging. This LED might also flicker if the battery is not connected.

Power supplies

You have a lot of power supply options here! We bring out the BAT pin, which is tied to the lipoly JST connector, as well as USB which is the +5V from USB if connected. We also have the 3V pin which has the output from the 3.3V regulator. We use a 500mA peak low-dropout regulator. While you can get 500mA from it, you can't do it continuously from 5V as it will overheat the regulator. We use this to power the ESP8266 which can draw spikes of 250+mA (although its not continuous).

You should be able to budget about 250mA current available from the regulator, which will leave plenty for the WiFi module.

Measuring Battery

If you're running off of a battery, chances are you wanna know what the voltage is at! That way you can tell when the battery needs recharging. Lipoly batteries are 'maxed out' at 4.2V and stick around 3.7V for much of the battery life, then slowly sink down to 3.2V or so before the protection circuitry cuts it off. By measuring the voltage you can quickly tell when you're heading below 3.7V

Don't forget to install the USB driver for the CP2104 USB-to-Serial chip!

Open up serial console

Next up, on your computer, use a serial console program such as CoolTerm (Mac) or Putty (Windows) or screen (linux). Teraterm seems to dislike the initial 74400bps data stream from the ESP8266 so you can try it but you'll possibly need to reset the terminal software.

Connect up to the COM or Serial port used by your cable, at 9600 Baud

Make sure you have turned off any hardware handshake or flow control

Putty isn't good with pasting code in, so you may not be able to copy-n-paste!

Also make sure you have line endings set to CRLF "\r\n"

Use any serial console program you like, we just happen to be used to Putty!

Once the terminal software is connected, click the Reset button on the Feather HUZZAH ESP8266 board to reset it and have it print out the welcome message:

If you don't get this message, first check that the red/blue leds flickered when you press the reset button. If they didnt, make sure you've got the right baud rate selected in the software (9600)

Hello world!

Ok we can now turn on an LED. There is a red LED on each board, connected to GPIO #0

NodeMCU Lua's pinouts are not the same as the Arduino/gcc pinouts. We print the Arduino pinouts on the board so watch out!

The Lua documentation for the ESP8266 has GPIO #4 and #5 swapped so if #4/#5 aren't working for you, try swapping!

Pin Notes

PCB/Arduino

NodeMCU/Lua

No pullups!

0

3

2

4

3

9

4

1

5

2

9

11

10

12

12

6

13

7

14

5

15

8

16

0

So to set the pin #0 LED on and off (which would be pin #3 in Lua) first make it an output:

For longer text, pasting can be difficult as the lua interpreter needs a little delay time between characters and also require CR-LF settings. For that reason you may want to paste each line and then hit return manually.

We can connect to the access point with wifi.sta.config and wifi.sta.connect - it will take a second or two to complete the connection, you can query the module to ask the status with wifi.sta.status() - when you get a 5 it means the connection is completed and DHCP successful

This is just a light overview of testing out your HUZZAH ESP breakout! For much more, check out NodeMCU's documentation page https://nodemcu.readthedocs.io/ for the details on what functions are available to you, as well as http://www.lua.org to learn more about the Lua scripting language

If you are using Mac OS 10.12.6 (Sierra) and you cannot upload with the latest Mac OS VCP driver, please try the legacy v4 driver below. Note you will need to uninstall the v5 driver using uninstall.sh (in the driver package)

Schematic

Fabrication Print

ESP8266 F.A.Q.

When I connect stuff to some of the pins, the Huzzah stops working. Whats up with that?

The ESP8266 uses some of the pins as 'boot mode' pins so on boot they must be set to certain values:

CH_PD (EN) should be always pulled high (it will disable the entire module if low)

RST should be always pulled high (it will disable the entire module if low)

GPIO 0 sets whether the bootloader is active, it must be pulled HIGH during power up/reset for the user program to run. If it's pulled LOW, it will activate the bootloader. The built-in red LED on #0 pulls it up

GPIO 2 must be pulled high on power up/reset.

GPIO 15 must be pulled low on power up/reset.

My Huzzah board keeps crashing and resetting, whats up with that?

The most common reason for crashes is power failure. Make sure you're powering the Huzzah with a good ~5V power supply, and if you're using a USB-Serial cable, that it's plugged into the mainboard of your computer or through a powered hub!

I can't seem to find the Serial port on my computer for the Feather HUZZAH?

I still can't seem to find the Serial port on my computer for the Feather Huzzah!

Many cheap electronics come with charge-only USB cables, which cause headaches later. Make sure you are using a proper data/sync USB cable. If you find a cable that is charge-only (not data/sync also) throw it out so you don't have the same problem again.

In the Arduino15 folder, go into packages, and delete the folder esp8266

Go back to the Arduino IDE, and install ESP8266 board support.

Now go back to the Finder, and check that you have the xtensa-lx106-elf-g++ file in the path Arduino15/packages/esp8266/tools/xtensa-lx106-elf-gcc/1.20.0-26-gb404fb9-2/bin/xtensa-lx106-elf-g++

That's it!

Whenever I start or reset the ESP8226 there's a bunch of "gibberish" on the Serial console

This is the ROM debug messages, it's transmitted at 74880 baud so you rarely see it in proper 'ascii output' - instead usually it gets corrupted into a bunch of strange characters.

I'm having difficulties uploading to the HUZZAH with the Arduino IDE

Make sure you're using a good quality USB/Serial cable. Install the official drivers for that cable too! We've also noticed that PL2303-based cables don't work on Macs for some reason. FTDI or CP210x based chipsets work best

I tried that, but I'm still having difficulties uploading with the Arduino IDE

Sometimes, it helps to switch the board type to "Generic ESP8266 Module". Set the Reset Method to "nodemcu"

I'm stuck in bootloader mode and can't upload

You say your led is stuck on dim and you get an error trying to upload? And you're sure your serial cable is connected and working correctly? Well, here's a potential fix: Connect the GPIO0 pin to GND through a 220 ohm resistor. Leave it connected while you upload. You may have to try it a couple of times, but it should eventually upload and get the HUZZAH unstuck from bootload mode! You can then remove the resistor connection, and your HUZZAH will be happy ever after!

(Note: you may also have to tie RST and EN (CH_PD) together to get this to work. Remove the connection once you have the module programmed).

I can't get Lua to respond to my commands

Make sure your terminal software is sending correct line endings! The default PuTTY settings may be wrong when trying to talk to Lua on an ESP8266. Lua expects CRLF "\r\n" line endings, and apparently PuTTY defaults to just LF "\n"!

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